Bone cements

Bone ash Bone black Bone cement Bone coal Bone density... 

Recommended Practice for Scleroscope Hardness Testing MetaUic Materials Rockwell Hardness of Bone Cements... 

Medicine. The polymethacrylates have been used for many years in the manufacture of dentures, teeth, denture bases, and filling materials (116,117) (see Dental materials). In the orthodontics market, methacrylates have found acceptance as sealants, or pit and fissure resin sealants which are painted over teeth and act as a barrier to tooth decay. The dimensional behavior of curing bone-cement masses has been reported (118), as has the characterization of the microstmcture of a cold-cured acryUc resin (119). Polymethacrylates are used to prepare both soft and hard contact lenses (120,121). Hydrogels based on 2-hydroxyethyl methacrylate are used in soft contact lenses and other biomedical appHcations (122,123) (see Contactlenses). 

The materials used in a total joint replacement ate designed to enable the joint to function normally. The artificial components ate generally composed of a metal piece that fits closely into bone tissue. The metals ate varied and include stainless steel or alloys of cobalt, chrome, and titanium. The plastic material used in implants is a polyethylene that is extremely durable and wear-resistant. Also, a bone cement, a methacrylate, is often used to anchor the artificial joint materials into the bone. Cementiess joint replacements have mote tecentiy been developed. In these replacements, the prosthesis and the bone ate made to fit together without the need for bone cement. The implants ate press-fit into the bone. 

The acetabular component is as integral to successful total hip arthroplasty as is the femoral hip stem component. The life of the acetabular component depends on proper placement and bone preparation in the acetabular region of the hip girdle, proper use of bone cement, and superior component design. 

In 1971 a metal-backed polyethylene acetabular cup was introduced. This cup provided an eccentric socket which was replaceable, leaving the metal and replacing only the polyethylene. Because of the success of this component, metal-backed high density polyethylene (HDPE) liner is standard for prosthetic acetabular components. Research confirms that metal-backing reduces the peak stresses in the bone cement, and that HDPE forms a successfiil articulating surface for the prosthetic joint. 

Dentures require accurate fit, reasonable chewing efficiency, and lifelike appearance (189). The chewing efficiency of artificial dentures is one-sixth that of natural dentition (190). AcryHc resins are generally used as powder/Hquid formulations for denture base, bone cement, and related appHcations. Polymerization is achieved thermally using initiators photochemicaHy using photoactive chemicals and either uv or visible light irradiation and at ambient temperatures using initiator/activator systems. 

Organic peroxide-aromatic tertiary amine system is a well-known organic redox system 1]. The typical examples are benzoyl peroxide(BPO)-N,N-dimethylani-line(DMA) and BPO-DMT(N,N-dimethyl-p-toluidine) systems. The binary initiation system has been used in vinyl polymerization in dental acrylic resins and composite resins [2] and in bone cement [3]. Many papers have reported the initiation reaction of these systems for several decades, but the initiation mechanism is still not unified and in controversy [4,5]. Another kind of organic redox system consists of organic hydroperoxide and an aromatic tertiary amine system such as cumene hydroperoxide(CHP)-DMT is used in anaerobic adhesives [6]. Much less attention has been paid to this redox system and its initiation mechanism. A water-soluble peroxide such as persulfate and amine systems have been used in industrial aqueous solution and emulsion polymerization [7-10], yet the initiation mechanism has not been proposed in detail until recently [5]. In order to clarify the structural effect of peroxides and amines including functional monomers containing an amino group, a polymerizable amine, on the redox-initiated polymerization of vinyl monomers and its initiation mechanism, a series of studies have been carried out in our laboratory. 

Resorption of bone in the medial neck places the forces of continued weight bearing on the bone cement in that area and may lead to medial and/or distal migration of the femoral cement and prosthetic component ... 

Poly(methyl methacrylate) Hard and soft contact lenses, bone cement for artificial joints, intraocnlar lenses, dentnres... 

The PMMA bone cement is formed from a mixture of prepolymer PMMA powder, which contains a free-radical initiator, and liquid MMA monomer. In the operating theatre the powder and liquid are mixed, causing the initiator to dissolve and bring about polymerisation in the monomer component. The powder pre-polymer does not dissolve in the monomer but remains in the newly polymerised materials as a kind of reinforcing filler. 

Once polymerisation is complete, the components of the new hip joint can be connected together and the operation completed. This surgical procedure has been very successful over the past 30 or so years and now an estimated 45 000 such operations are carried out each year in the UK alone. Similar procedures are used for the replacement of both arthritic knees and arthritic fingers, though these latter operations are less common than hip replacements. Overall considerable amounts of PMMA are used each year as bone cements for these surgical procedures. 

Only two of these materials are of practical importance the zinc polycarboxylate cement of Smith (1968) and the glass-ionomer cement of Wilson Kent (1971). Both are used in dental applications and both have been used as bone cements. The glass-ionomer cement is, perhaps, the most versatile of all AB cements. It has many applications in dentistry a... 

The glass polyalkenoate cement uniquely combines translucency with the ability to bond to untreated tooth material and bone. Indeed, the only other cement to possess translucency is the dental silicate cement, while the zinc polycarboxylate cement is the only other adhesive cement. It is also an agent for the sustained release of fluoride. For these reasons the glass polyalkenoate cement has many applications in dentistry as well as being a candidate bone cement. Its translucency makes it a favoured material both for the restoration of front teeth and to cement translucent porcelain teeth and veneers. Its adhesive quality reduces and sometimes eliminates the need for the use of the dental drill. The release of fluoride from this cement protects neighbouring tooth material from the ravages of dental decay. New clinical techniques have been devised to exploit the unique characteristics of the material (McLean Wilson, 1977a,b,c Wilson McLean, 1988 Mount, 1990). 

This cement also has a low setting exotherm, lower than any other aqueous dental cement (Crisp, Jennings Wilson, 1978), which means that it can be mixed swiftly as there is no need to dissipate heat. This property also gives it an advantage over bone cements based on modified poly(methyl methacrylate) which have high exotherms. 

Jonck, L. M. Grobbelaar, C. J. (1990). lonos bone cement (glass-ionomer) an experimental and clinical evaluation in joint replacement. Clinical Materials, 6, 323-59. 

Petty, W. (1980). Methylmethacrylate concentrations in tissues adjacent to bone cement. Journal of Biomedical Materials Research, 14, 88-95. 

Pople, I. K. Phillips, H. (1988). Bone cement and the liver. A dose-related effect Journal of Bone and Joint Surgery, 70B, 364-6. 

Discuss the possible impact of antibiotic-impregnated bone cement and how this affects the use of antimicrobial prophylaxis in surgery. 

Further study is needed before antibiotic-impregnated bone cements can be recommended as an alternative to preoperative prophylaxis with traditional antimicrobials. 

Bioactive PMMA bone cement prepared by modification with methacryloxypropyltrimethoxy silane and calcium chloride. Journal of Biomedical Materials Research, 67A, 1417-1423. 

Mori, A., Ohtsuki, C., Sugino, A., Kuramoto, K., Miyazaki, T., Tanihara, M. and Osaka, A. (2003)Bioactive PMMA-based bone cement modified with methacryloxypropyltrimethoxysilane and calcium salts — Effects of calcium salts on apatite-forming ability. Journal of the Ceramic Society of Japan, 111, 738-742. 

Shinzato, S., Kobayashi, M., Mousa, W.F., Kamimura, M., Neo, M., Kitamura, Y., Kokubo, T. and Nakamura, T. (2000) Bioactive polymethyl methacrylate-based bone cement Comparison of glass beads,... 

We chose to modify the anhydride monomers with photopolymerizable methacrylate functionalities. Methacrylate-based polymers have a long history in biomedical applications, ranging from photocured dental composites [20] to thermally cured bone cements [21]. Furthermore, photopolymerizations provide many advantages for material handling and processing, including spatial and temporal control of the polymerization and rapid rates at ambient temperatures. Liquid or putty-like monomer/initiator... 

The ultimate success of methyl methacrylate bone cements in surgical arenas depends on its application at an appropriate viscosity. Recent studies have raised concerns that the long-term stability of bone cements may be compromised by the empirical way in which the setting of samples is determined [6]. The literature from one manufacturer states that, in addition to the concentration effects one would expect in a biphasic free-radical... 

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